NodeWiz-R: um sistema P2P relacional para a descoberta de recursos.

Abstract

With the ever increasing popularity of the Internet, great opportunities for large-scale resource sharing have emerged. Shared resources can be of several types, ranging from mul- timedia content files, documents, through massive data produced by operational research centres, until computers and services that perform processing and storage of information. The first requirement to enable resource sharing is the existence of a service that allows users to find what resources are available, and where. In a system with the Internet scale and dinamicity, it is necessary that the discovery service is distributed and autonomous. Although several solutions have been proposed for distributed and autonomous resource discovery ser- vices on the Internet, they all fail to provide at least one of the following important features: i) an expressive way to annotate resources, through its associated attributes; ii) efficient ways to index these attributes; and iii) high matching rates in the requests processed. In this work, we present NodeWiz-R, a distributed and self-managed resource discovery solution that im- plements a relational model atop of a peer-to-peer substrate to simultaneously provide all these three features. NodeWiz-R implements several indexing levels that enables it to find resource information, described using the relational model, in an efficient manner. In order to keep the system load balanced, the relational model tables are fragmented horizontally over the network. The solution supports expressive queries processing using the standard SQL language. Results obtained by simulations and confirmed by experiments with the system prototype, indicate that NodeWiz-R is more efficient than other flooding based solutions for distributed SQL query processing.